Compartmentalized expression of three novel sarco/endoplasmic reticulum Ca2+ATPase 3 isoforms including the switch to ER stress, SERCA3f, in non-failing and failing human heart.
The human sarco/endoplasmic reticulum (ER) Ca(2+)ATPase 3 (SERCA3) gene gives rise to SERCA3a-3f isoforms, the latter inducing ER stress in vitro. Here, we first demonstrated the co-expression of SERCA3a, -3d and -3f proteins in the heart. Evidence for endogenous proteins was obtained by using isoform-specific antibodies including a new SERCA3d-specific antibody, and either Western blotting of protein lysates or immunoprecipitation of membrane proteins. An immunolocalization study of both left ventricle tissue and isolated cardiomyocytes showed a distinct compartmentalization of the SERCA3 isoforms, as a uniform distribution of SERCA3a was detected while -3d and -3f isoforms were observed around the nucleus and in close vicinity of plasma membrane, respectively. Second, we studied their expressions in failing hearts including mixed (MCM) (n=1) and idiopathic dilated (IDCM) cardiomyopathies (n=4). Compared with controls (n=5), similar expressions of SERCA3a and -3d mRNAs were observed in all patients. In contrast, SERCA3f mRNA was found to be up-regulated in failing hearts (125+/-7%). Remarkably, overexpression of SERCA3f paralleled an increase in ER stress markers including processing of X-box-binding protein-1 (XBP-1) mRNA (176+/-24%), and expression of XBP-1 protein and glucose-regulated protein (GRP)78 (232+/-21%). These findings revisit the human heart's Ca(2+)ATPase system and indicate that SERCA3f may account for the mechanism of ER stress in vivo in heart failure.
Dally
Saoussen
S
Inserm, U 689, CRCIL, Hôpital Lariboisière, 41 Boulevard de la Chapelle, 75475 Paris Cedex 10, France.
Monceau
Virginie
V
Corvazier
Elisabeth
E
Bredoux
Raymonde
R
Raies
Aly
A
Bobe
Régis
R
del Monte
Federica
F
Enouf
Jocelyne
J
D000328:Adult; D002451:Cell Compartmentation; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000201:enzymology* / Q000473:pathology*; D000091342:Endoplasmic Reticulum Chaperone BiP; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D006333:Heart Failure / Q000201:enzymology* / Q000235:genetics; D006360:Heat-Shock Proteins; D006801:Humans; D042541:Intracellular Space / Q000201:enzymology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D018832:Molecular Chaperones; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D032383:Myocytes, Cardiac / Q000201:enzymology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000071701:Regulatory Factor X Transcription Factors; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D000071717:X-Box Binding Protein 1
D004268:DNA-Binding Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D007527:Isoenzymes; D018832:Molecular Chaperones; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506949:ATP2A3 protein, human